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This article analyzes and describes phase nonlinearity reduction techniques in detail for ultra wideband complex receivers to qualify airborne system requirements. Phase nonlinearity directly affects the final frequency resolution coming from unknown threats. Thereby, the reduction of phase nonlinearity of all radio frequency (RF) channels including phase correlators is very essential. A simple phase nonlinearity calculation step has been shown in this article without taking the help of any coding (software). A detail excel sheet–based phase nonlinearity calculation has been explained and estimated with examples. Power and phase corrections are especially done to keep the RF response flat over a wide frequency spectrum to enhance better phase linearity. This is done by designing various equalizers with different slope gradients and adjusting power levels by using attenuation pads or reducing feeds by other means. Phase nonlinearity has been kept under control by tracking the phase of mixers, other passive/active components within ±5°, and all the RF channels within ±15°. The power level has been adjusted within P1dB or just beyond the P1dB to keep the harmonic level less, which in turn controls phase nonlinearity in all the active devices. The performance of phase correlators against various power levels has been analyzed to finalize uniform RF and LO power levels (feed) at the input of the phase correlators. The level of uniform feed has been decided after reviewing phase nonlinearity responses of the correlators. Thus, the final resolved frequency become accurate (<3 MHz root mean square). Finally, four receivers have successfully been developed and evaluated over temperature (−40°C to +71°C) and vibration to establish the method for mass production.

This article describes various housing design strategies of a complex receiver system to overcome EMI/EMC challenges for airborne system applications. Isolation of leakage energy between various RF/DC-DC converters/Regulators/pulsing blocks are the key target of this design to keep conductive and radiative emission minimum. Hence, complex receiver design has been segregated into various modules. Block level design is carried out using 3D EM simulator to assess the leakage. Then they are stacked together very tactfully within the specified area without compromising inter-channel/module interference between them and the form factor respectively. The super compact stacks are further channelized for RF, DC supply, controls etc. and protected them from any kind of interferences. Low cost flexi interconnects are made to interface various stacks to arrest unwanted high/low frequency leakages. Finally, receiver module is developed and tested over temperature and EMI/EMC successfully to establish the methodology.